I thought I would share an update on a recent change I made in my imaging setup. I got started in astrophotography in early February 2014. While I think I had done enough research to hit the ground running in terms of getting subs, integrating them, and processing them...I was really a total noob when it came to equipment. I had a tough time following some recommendations, such as to get custom scope rings made by Parallax Instruments (couldn't ever get ahold of the guy, over email or phone, to request special made rings in the dimensions I needed.) I understood that rings would help stabilize my scope and minimize flexure vs. just attaching my lens tripod foot to a dovetail (which cantilevers the bulk of the huge 600mm lens out over nothing), but I kind of gave up on the idea of getting scope rings after a few weeks of trying to reach Parallax Instruments. It was often recommended that I pick up some larger scope rings with three point adjustment bolts, but I never wanted to do that, as the lens is $13,000, and I have rings like that for my Orion ST80 that I use as a guidescope, and the rings have scratched the hell out of it. I simply couldn't afford to damage my expensive lens.

As you can see from the image above, I've been using an ADM Dual Side-by-Side saddle since I started, along with a few other various ADM bits and pieces such as adjustable guidescope rings and a dual male dovetail. I ultimately spent quite a bit on ADM parts, when as I now know, I really didn't need to. I recently found cradle rings at ScopeStuff. They normally come in sets of two, however I gave them a call, and the guy on the phone (I don't exactly remember his name, Jim maybe?) was willing to sell me two rings of differing size. I picked up a 6" and 4" cradle-type scope ring without any adjustment bolts, which are the sizes I needed to hold the front end of the scope, as well as the back end. I also picked up some of their scope ring felt...however that's turned out to be a bit too thick, so I have to find a way of shaving it down to a point where I can securely tighten down on my lens without causing damage. I also ordered ANOTHER ADM dovetail, this time a nice large D-type Universal 15", which is only a few inches longer than the span from the front to back ring on my lens. Finally, I went to the hardware store and picked up a crapload of large washers, and some 1/4" 20 hex-cap screws that were long enough to reach through the dovetail, through the washers, and into the mounting holes on the scope rings.

I was going to have some custom riser blocks made, however in the end, I decided I wanted more flexibility, as I've had problems with cone error, and it would be really nice to just add or remove a washer or two to get rid of most of that, then maybe shim a bit more with a few layers of aluminum foil. It was a lot cheaper to do that, too. I also wanted flexibility, as in the long run, I plan to pick up the Canon EF 300mm f/2.8 L II as well. Also for my bird and wildlife photography, it'll double as a nice ultra wide field lens, or give me the option of picking up one of Sony's newer ultra low noise, high QE CCD sensors (which are rather tiny) and still have a good field of view (I love wide field.) Anyway, using washers, it won't be difficult to readjust the rings for use with the 300mm, which I think should be compatible with the 6" ring, and is definitely compatible with the back 4" ring.

One of the nice things about ScopeStuff's rings is they have mounting threads sunk on both the top and bottom. That gives me the option of attaching another V-type dovetail on the top, to which I can attach other accessories...guidescope and/or maybe find some way of piggybacking my other DSLR for wide field shots. I plan to eventually pick up the ADM 14" V-type Universal dovetail to do that, but for now, I was able to mount my Orion 50mm Mini Guidescope directly to the top of the front 6" scope ring. I went and picked up another 1/4" 20 hex cap screw to bold that in, and used a couple of washers to get a REALLY tight fit. When I originally used the Orion 50mm mini, I had some fairly severe flexure problems. I think it was due to both not having the base plate for the guidescope securely mounted to the dovetail, and also due to the fact that one of the adjustment screws actually turned out to be stuck. They seem to be plastic, however, and as I was messing around with it recently I managed to fix that, and the guidescope can now be locked down very tight with very little flexure.

Overall, the whole setup, both the guidescope and the lens, are very securely tightened in place now, and there is very little flexure left. I'm sure there is still some differential flexure, however I took a few test exposures up to 15 minutes, and I did not see any visible star stretching. Moving from the side-by-side to a single dovetail has also done wonders for the moment of inertia. I think that took care of a lot of slop in my setup, which may have been contributing to a long-standing dec guiding problem as well. Overall, I'm extremely happy with the setup as it is now, although in the long run, I think adding a vixen to the top will be the final touch that will complete the setup. Using scope rings has the added benefit of not requiring me to remove and re-add the large scope dovetail when I want to do other photography (I originally purchased the 600mm lens for my bird and wildlife photography.) I can leave the standard Arca-Swiss dovetail attached to the tripod foot, and the lens just drops into the two rings (they clamshell open.)

It works, although to power both peltiers at once from AC, I'm going to need a full blown power supply. I think for now I'll just plug the opening in the insulation for the second peltier, and just use the one, so I can power it off of a standard 12v 5a AC/DC converter. It still needs some work. I had to tweak the design a couple times to get it to work properly with the DSLR and an EF lens. I had to create a space for the grip on the right, then it turned out to be too difficult to get the lens on and off through an opening in the inner copper housing, so I finally changed the design to a "drop-in". I am still working on getting that designed right. I scratched up my new 5D III a little bit slipping it on, so I think I need to grind down the edge of the metal more, and fashion some kind of insulation to fit around the edge of it so it is more of a "soft slip" that I can just drop the camera, with lens attached, right into. I'll also need to find a way to fully insulate the front, as at the moment, there are some gaping holes that will cost me all my cooling energy. Maybe a two-part piece of the extruded foam insulation I can place around the lens, and clamp onto the front.

Building a cold box for a DSLR+EF lens ultimately turned out to be a lot more difficult than building a "standard" cold box, one that can just be square, for use with a T-adapter on a scope. I'm hoping, in the end, that I can get it all figured out and properly insulated, as I've sunk a decent amount of money into copper, peltiers, and Arduino+electronics stuff so far.

Impressive setup. It looks very solid. I recently made a mount so that I could use my Nightscape camera with Pentax lenses (just posted); I had to get around not having a tripod socket on the Nightscape body. My largest telephot lens is only 200 mm so I could get away with a less robust holder than you have made.

I'm very interested in the cold box you made. Summer nights are hot here, and my camera only has single stage cooling, so I've been thinking about how to supply additional cooling. Thanks for sharing the images.

Thanks guys. I've already done some imaging. My star problems that I was having before, the whole halo effect where the center of the stars got dark, or looked like buttons, seems to be gone. I don't really know why that was occurring, but my stars are now much better, rounder. I got some subs for bubble, lobster, and the surrounding clusters. I don't have enough subs to really share anything yet, but I was able to just start my sequence, and just let it run. Once I got it rolling, I really didn't have to fiddle with anything. It was pretty awesome.

I also bumped up to 840mm, with my 1.4x TC. Image scale is smaller (I might just barely be overampling now), and I went from 240-270 second exposures to 480 second exposures. Despite the longer focal length and longer exposures, things still look better.

Something seems to be adding a character to the end. Copy and paste, that seems to work.

They look beautiful, thanks for the link.

Are all those images in at 600mm? More specifically the one of Orion. I'm between buying a at6rc with an atlas or using my 70-300mm f/_._-5.6 with an atlas. I'd like to avoid buying an astrograph because like you, I'm into both wildlife and astro. I only have a tripod, so a single exposure of Andromeda doesn't give me any indication of how big it really is in the frame. I'm not able to gather light long enough and 5.6 really isn't too great I find.

Yeah, all my images are with the 600 so far. Now that I've got my setup more balanced, with a tighter moment, and guiding better, I am going to start playing with 840mm f/5.6 (600 + 1.4x) and 1200mm f/8 (600mm + 2x). I already started imaging bubble and lobster nebulas at 840mm, and it's got some of the best quality stars I've ever had so far (with seeing of 4.1 FWHM.)

I will be getting an astrograph at some point. At the very least, the AT8RC, although I'd really like a larger scope than that. The big wide field of the 600 isn't all that great for galaxies...you really need more focal length to get good resolution on them. I don't think I'll do that until next year's galaxy season, as from now until then, there are plenty of good large nebula targets and a couple of larger galaxies (Andromeda and Triangulum) to image.

Yeah, all my images are with the 600 so far. Now that I've got my setup more balanced, with a tighter moment, and guiding better, I am going to start playing with 840mm f/5.6 (600 + 1.4x) and 1200mm f/8 (600mm + 2x). I already started imaging bubble and lobster nebulas at 840mm, and it's got some of the best quality stars I've ever had so far (with seeing of 4.1 FWHM.)

I will be getting an astrograph at some point. At the very least, the AT8RC, although I'd really like a larger scope than that. The big wide field of the 600 isn't all that great for galaxies...you really need more focal length to get good resolution on them. I don't think I'll do that until next year's galaxy season, as from now until then, there are plenty of good large nebula targets and a couple of larger galaxies (Andromeda and Triangulum) to image.

Given your experience shooting with a standard (although not so standard in your case haha) lens, would a 300mm 5.6 mounted on an equatorial be short of enough to produce strong sharp images of galaxies and maybe neubulas? I'm shooting with a dx camera and fx lenses. Although (in its time) it was nikons high end dx camera (d7000), it still doesn't handle high iso very well, so cropping isn't an option for me.

The new Tamron 600mm looks decent, spa a teleconverter on there and id be all set, but it still isnt very fast. Might be a good wildlife and astro combo though..

Given your experience shooting with a standard (although not so standard in your case haha) lens, would a 300mm 5.6 mounted on an equatorial be short of enough to produce strong sharp images of galaxies and maybe neubulas? I'm shooting with a dx camera and fx lenses. Although (in its time) it was nikons high end dx camera (d7000), it still doesn't handle high iso very well, so cropping isn't an option for me.

The new Tamron 600mm looks decent, spa a teleconverter on there and id be all set, but it still isnt very fast. Might be a good wildlife and astro combo though..

I shoot with a Nikon D7100 and use the Nikon 70-300mm f4-5.6 currently mounted on an iOptron SkyTracker. There's no way you are going to get " strong sharp images of galaxies " other than Andromeda, with a 300mmm or even a 600mm lens, even heavily cropped. For that you're going to need the RC and something preferably larger than the 6".

On the flip side, many nebula are large enough, that 300-600mm is almost too much.

Buy the Atlas, keep your existing gear, and first learn the the hurdles of long exposure photography. I bought my Atlas 1 1/2 months ago, to mount the D7100 with my 80mm APO refractor, and other than a few dry runs in the living room, haven't had a chance to actually set it up outside until the past few nights. It's taken me two evenings to even get confident enough, to start thinking about attaching the camera, maybe after a few more nights of getting used to the mount, alignment, hand controller etc..